Hello there Natgold. We have read your message. We try to help you. firewall or antivirus software that blocks outgoing e-mail is a known cause for not being able to send messages after updating Thunderbird, since it can be set to trust the previous version of Thunderbird and no longer recognizes the new version as trusted. Remove Thunderbird from the list of trusted programs in its program list, and then add it manually or when prompted to correct it. http://kb.mozillazine.org/Cannot_send_mail Greetings Firefox Volunteer.